Method for the prevention of motion sickness, and apparatus for detecting and signaling potentailly sickening motions

ABSTRACT

A method for the prevention of motion sickness in occupants of a vehicle, wherein a motion sickness indicator is fitted in the vehicle, which indicator indicates whether the vehicle motions experienced by the occupants during use can cause motion sickness, wherein the information coming from the indicator is fed back to a driver or a steering system of the vehicle, all this in such a manner that the driver or steering system can adjust the steering of the car in such a manner that the sickening motions are minimized. Further more, the invention relates to a motion sickness indicator suitable for a method according to the invention, comprising a transducer for measuring a relevant parameter for motion sickness, evaluation means for comparing the measured motion parameter with empirical data concerning the sickening effect of comparable motion parameters, on the basis of which the sickening effect of the measured parameter can be estimated, and rendering means for presenting an outcome obtained by means of the evaluation tools to the user in a suitable manner.

The invention relates to a method for the prevention of motion sickness,and an apparatus for detecting and signaling potentially sickeningmotions suitable for application in a method according to the invention.

Motion sickness can arise when a person is exposed to one or morespecific motions for a longer period of time. In addition, factors suchas temperature, smell, mood and digestion can play a catalyzing role.The best-known forms of motion sickness are sea sickness and carsickness. Especially the latter variant occurs frequently, in particularin children. Many solutions have already been proposed to control motionsickness in general, and car sickness in particular.

For example, there are pharmaceutical preventatives on the market, whichneed to be ingested some time before a drive and then help to suppressthe motion sickness and the accompanying clinical picture, such asnausea. These known preventatives are generally not without side effectsand so they are not suitable for every one or in every situation. Thisis also why the preventatives are less suitable for frequent, forexample daily use. In addition, it is inherent to their preventativenature that, in part of the cases, these preventatives will be takenunnecessarily, since they need to be ingested at a moment when it is notcertain at all yet whether one will be motion sick during the driveinvolved.

Further, from various patents, for example U.S. Pat. No. 5,647,835 andU.S. Pat. No. 5,161,196, car sickness preventatives are known, whoseaction is based on deception of the senses, particularly sight andhearing. Specific auditory or visual signals are blocked or replacedwith artificial, non-sickening sensory signals. For instance, it isknown to present passengers with an artificial visual and/or auditoryhorizon. However, these solutions require complicated, expensiveequipment and thus seem little suitable for practical daily use, forexample in a bus or passenger car.

The object of this invention is a method for the prevention of motionsickness in occupants of a vehicle, wherein the abovementioneddisadvantages of the known methods mentioned above have been avoided.For that purpose, a method according to the invention is characterizedby the measures according to claim 1.

In a method according to the invention, a vehicle is provided with amotion sickness indicator, which, in an early stage, alerts a driver ora steering system of the vehicle to potentially sickening vehiclemotions. On the basis of this information, the driver or steering systemcan change the steering of the vehicle in such a way that the sickeningmotions are avoided or, in any case, do not continue over a longerperiod of time. Thus, a method according to the invention does notinvolve intervention in the motion-sick person, as known preventativesand methods do, but primarily in the causative source, the vehiclemotions. This has a number of advantages. For example, a methodaccording to the invention is more efficient than many of the knownpreventatives, in that this method can help all occupants of a vehicleat the same time, without having to intervene in each of themseparately. This is especially advantageous in large vehicles with manypassengers, for example buses. Furthermore, this method causes noadverse side effects in the passengers and is thus suitable for everyone, in every situation, as long and as often as needed. In addition,the method, in contrast to many of the known preventatives, has a widepractical applicability, since the method can be carried out withrelatively simple auxiliary means (in particular a motion sicknessindicator to be discussed in more detail below). These auxiliary meanscan simply be fitted in any vehicle or even to one of the passengers,without requiring radical adaptations. In order for the method tofunction properly, it is only important that the motions of the vehiclecan be influenced by a driver or steering system of that vehicle to asufficient degree. If desired, the method can simply be ‘switched off’,for example when none of the occupants is susceptible to motionsickness. In that case, the driver can simply ignore the informationprovided by the indicator or switch off the motion sickness indicator.

A suitable motion sickness indicator for the method can be embodied invarious manners. In a simple embodiment, the indicator can comprise, forexample, a mass spring system or a body immersed in a liquid that is atrest during permissible vehicle motions and is excited by sickeningmotions. Then the degree of excitation is a measure for the gravity ofthe sickening motion.

In a more advanced embodiment, the motion sickness indicator cancomprise measuring, evaluation and rendering means, with which thevehicle motion, at any rate at least one of its relevant parameters formotion sickness, is measured and compared with permissible values ormotion patterns that are stored in evaluation means. Then, the outcomeof this comparison can be presented to the driver with the aid ofsuitable rendering means. Such a motion sickness indicator canaccurately and timely identify sickening motions and, in addition,provide the driver with further information concerning, for example, thedegree of sickening of the motions generated by his steering. Inaddition, the effect of correcting steering actions can be visualizeddirectly.

In a further elaboration, a method according to the invention ischaracterized by the measures according to claims 3-5.

Research has shown that the acceleration of a motion is a relevantparameter for motion sickness. The acceleration can simply be measuredand then compared with a relation between acceleration and motionsickness known from practice. It has been found that on the basis of anacceleration measured in only one direction, a correct prediction canalready be made with regard to the sickening effect of a motion. Sincemotions in general and vehicle motions in particular can usually beprovoking with regard to motion sickness in several directions, theaccuracy of the prediction can be increased by measuring theacceleration of the vehicle motions three-dimensionally, in other words,in three orthogonal directions. Then the degree of sickening can bepredicted for each separate direction. However, preferably one totalacceleration signal is calculated on the basis of the three measuredacceleration components, after which the prediction is based on this onesignal. This provides has the advantage that the prediction needs to beperformed for just one signal, while yet the influence of all threeacceleration components is incorporated in this prediction. A secondadvantage is that this makes the orientation of the measuring means inrelation to the vehicle irrelevant. This is favorable in particular whenthe motion sickness indicator is not integrated in the vehicle, but isto be fitted in the vehicle as a loose instrument.

In a particularly advantageous embodiment, a method according to theinvention is characterized by the measures according to claim 6.

Further research of the applicant has shown that the relation betweenthe acceleration of a motion and the degree to which this motion cancause motion sickness in an average person can be approximated by atransfer function with a band pass characteristic. The response of anaverage individual to the vehicle motions can thus simply be predictedby filtering the measured acceleration signal of the motion with such aband pass characteristic. The filtered signal then gives a directindication of the gravity of the motion sickness. Optionally, thetransfer function can be adjusted to personal conditions with the aid ofadjustable weight and amplification factors.

Furthermore, the invention relates to an apparatus for detecting andsignaling potentially sickening motions, characterized by the measuresaccording to claim 8.

With an apparatus according to the invention it can be predicted whethera specific motion can cause motion sickness, when an individual, forexample a passenger of a vehicle, would be exposed to this motion for aprolonged time. For this purpose, the apparatus has been provided withmeasuring means for measuring a motion parameter that is representativeof motion sickness, for example an acceleration of the motion. Themeasured motion parameter is then, with the aid of evaluation meanspresent in the apparatus, compared with values or patterns known frompractice to be permissible from the viewpoint of motion sickness. Theevaluation means can also comprise an algorithm in which a relationbetween the motion parameter involved and its effect on motion sicknessis fixed, and on the basis of which the sickening effect of the measuredsignal can be estimated. In addition, the apparatus comprises renderingmeans, for example a LED, LCD display, alarm or loudspeaker, with whichthe outcome of the evaluation means can be communicated to the user.Optionally, signal processing means can be provided between themeasurement and evaluation means, for example for eliminatingmeasurement peaks and measurement noise, in order to obtain a reliableprediction.

In a particularly advantageous embodiment, an apparatus according to theinvention is characterized by the measures according to claims 10-12.

The applicant has demonstrated that the degree to which a motion cancause motion sickness can be predicted by the response of a band passfilter to the acceleration of the motions involved. Here, the band passfilter has a peak of around approximately 0.16 Hz, a first cut-offfrequency between approximately 0.01 and 0.16 Hz and a second cut-offfrequency between approximately 0.16 and 1 Hz. Such a band pass filtercan be used to evaluate the sickening effect of the signal measured bythe acceleration transducer in a simple yet accurate manner.

In a further elaboration, an apparatus according to the invention ischaracterized by the measures according to claim 13.

Since the evaluation means work with general data, based on the responseof an average person, the apparatus is preferably provided withadjustment means, in order to tune the sensitivity of the indicator tothe susceptibility of a specific interested party, for example apassenger. The adjustment means can comprise, for example, anamplification factor, by which the outcome of the evaluation means ismultiplied.

The adjustment means can be manually operated means, but can also be ofa self-learning nature. In the latter case, adjustment to the individualtakes place ‘automatically’, based on feedback information received fromthe individual during use. This self-learning embodiment is particularlyadvantageous when the apparatus is used by only one person or a smallnumber of persons. In the second case, preferably memory means areprovided, in which the personal preferred settings of different userscan be stored, so that these can be retrieved with a single preferencebutton.

In the further subclaims further advantageous embodiments of a methodfor the prevention of motion sickness and an apparatus for detectingpotentially sickening motions are described.

In order to clarify the invention, an exemplary embodiment of anapparatus according to the invention for detecting motions that causemotion sickness as well its operation and a possible application of thiswill be elucidated in more detail with reference to a drawing. In thedrawings:

FIG. 1 shows a schematic overview of the various parts of an apparatusfor detecting motions causing motion sickness according to theinvention;

FIG. 2 shows a transfer function of a suitable filter for application inan apparatus according to the invention, and

FIG. 3 shows a graphic representation of two alternative methods forevaluating the sickening effect of a measured signal.

FIG. 1 schematically shows an apparatus 1 according to the invention,hereafter also referred to as motion sickness indicator, for detectingmotions that potentially cause motion sickness. The motion sicknessindicator 1 comprises measuring means 3, evaluation means 5 connectedthereto, and connected to these evaluation means 5 rendering means 7.

The measuring means 3 are arranged for measuring a relevant parameterfor motion sickness of the motions. The applicant has demonstrated thatthe acceleration is such a relevant parameter. On the basis of theacceleration, a good prediction can be made with regard to the sickeningeffect of a motion. For this reason, the measuring means 3 comprise oneor more acceleration transducers with which the acceleration of a motionacting on the apparatus 1 during use can be measured, preferably inthree orthogonal directions (a_(x), a_(y), a_(z)). Optionally, theacceleration can be measured in two or only one direction, but sincemotions can generally be provoking with regard to motion sickness in allthree directions, the most accurate prediction can be obtained on thebasis of a three-dimensional signal. Acceleration transducers aresufficiently well-known from practice and therefore do not requirefurther specification.

The evaluation means 5 are used to predict the sickening effect of themotion on the basis of the measured accelerations. For this purpose, theevaluation means 5 comprise calculation means 8, comparison means 9 andadjustment means 10. The calculation means 8 are used to calculate atotal acceleration signal (a) on the basis of the measured accelerationcomponents (a_(x), a_(y), a_(z)), for example according to the followingunweighted addition:a={square root}{square root over (a _(x) ² +a _(y) ² +a _(z) ² )}.

The total acceleration signal (a) is then passed through the comparisonmeans 9. These comparison means 9 include knowledge gathered frompractice concerning the response of a normal population to such anacceleration signal. This knowledge can be incorporated in thecomparison means 9, for example, in the form of a table with permissiblethreshold values or a permissible acceleration pattern. Preferably,however, this knowledge is fixed in a dynamic model. It has been foundthat the degree to which an average individual gets motion sick due to aspecific motion can be modeled as a band pass characteristic, as shownin FIG. 2. This characteristic has both a high-pass and a low-passcharacter. The high-pass part is used to filter out the gravityacceleration component of the total acceleration signal (a). For thispurpose, the high-pass part has a first cut-off frequency (A) of, forexample, between approximately 0.01 and 0.16 Hz. The low-pass part has asecond cut-off frequency (C) of between approximately 0.16 and 1 Hz.With this, higher frequencies, above approximately 1 Hz, are filteredout, since these do not generally cause motion sickness. The peaksensitivity (B) of this characteristic is around approximately 0.16 Hz.Such a characteristic can be implemented in the evaluation means 5, forexample, in the form of a band pass filter.

Incidentally, motion sickness can also be predicted on the basis of theseparate acceleration components (a_(x), a_(y), a_(z)), whereby thesickening effect can be determined for each acceleration component,optionally with a separate filter. However, using the total accelerationsignal has the advantage that, because only the measured accelerationmagnitude is used as an input signal for the filter, the orientation ofthe acceleration transducer in relation to the vehicle becomesirrelevant. This is particularly favorable when the motion sicknessindicator can be fitted in the vehicle as a loose instrument.

Furthermore, in the evaluation means 5, an algorithm can be incorporatedthat, when evaluating the sickening effect of specific motions, takesthe factor time into account, in particular the period during which thesickening motions occur, the motion history of the vehicle from themoment of starting up, and the delay in the response of an averagepassenger to such sickening motions. For it is known that motionsickness normally becomes manifest only upon continued exposure tospecific motions. A time-dependent algorithm can factor this in.

Research by the applicant has shown that such a time-dependentevaluation algorithm can be modeled as a second-order low-pass filterwith a time constant which is round about 12 minutes. This isgraphically represented in FIG. 3, in uninterrupted lines, with aconstant vehicle motion being entered as a fictitious input signal. Thedegree of sickening (plotted on the vertical axis, on the left side ofFIG. 3) can be expressed, for example, as the percentage of a normalpopulation, which would actually have to vomit under the givenconditions. This degree will increase as the sickening motions are moreviolent and/or continue longer, while the degree will decrease when thesickening motions are temporarily less violent or even completelyabsent, for example because the driver of the vehicle reacts well to theinstantaneous degree and, on the basis of this, corrects his drivingbehavior, or, for example, because the vehicle is temporarilystationary.

Furthermore, in addition to or instead of the evaluation methodmentioned above, the evaluation means 5 can include an algorithm, whichcan monitor a cumulative measure, which quantifies the sickening effectover the whole drive. This measure is obtained by integrating theinstantaneous measure for motion sickness in the time. At a constantvehicle motion, this yields a straight line, as shown in FIG. 3 ininterrupted lines, the unit (plotted on the vertical axis, on the rightside) being arbitrary. As shown in FIG. 3, this measure only increasesin time.

Such a cumulative drive value has the additional advantage of storinginformation relating to the driving behavior of the driver. Thisinformation can be advantageously employed, for example, for didactic oradministrative purposes.

Furthermore, the evaluation means 5 comprise adjustment means 10, whichcan be used to adjust relevant factors for the evaluation, which canvary depending on user or condition of use, such as, for example, thetemperature in the vehicle, the age of the occupant or a personalsusceptibility factor, with which the susceptibility differences betweendifferent users can be factored in. Thus, this allows the indicator tobe optimally adjusted for every user and every situation.

The adjustment means 10 can be equipped in such a manner that the usercan adjust them manually, but they can also be of a self-learningnature. In the latter case, the adjustment means will, in the course ofuse, adopt an optimum value through interaction with the user.Preferably, memory means (not shown) are provided, in which preferredsettings for different users or conditions are stored, so these can beretrieved with a single preference button.

Furthermore, the motion sickness indicator 1 is provided with renderingmeans 7, with which the outcome of the evaluation means 5 can bepresented in a suitable manner. Depending on the type of information tobe conveyed, various rendering means 7 are possible. In a simplestembodiment, the rendering means 7 can comprise, for example, a LED oralarm signal to indicate whether the evaluated motions are sickening ornot. In a more advanced embodiment, the indicator 1 can also indicate towhat degree the motions are sickening, for example by means ofdifferently colored LEDs (green for non-sickening motions, orange whenthe motions are on the verge and red when the motions are sickening), amounting pointer, or an alarm with increasing volume or frequency.

In an even further elaborated embodiment, the motion sickness indicatorcan further give instructions on how to adjust the provocative motionsin order to minimize the sickening effect. Such information can be shownon an LCD display, for example.

An apparatus according to the invention can be used, for example, in avehicle to help the driver to control his driving behavior in such amanner that this is as little sickening as possible for a fellowpassenger. Since the driver himself does not usually get sick, it isdifficult for him to judge to what degree his driving style can causemotion sickness in fellow passengers. Of course these fellow passengerscan indicate this themselves, but then it is often too late, in otherwords, they already feel sick. A motion sickness indicator according tothe invention can be used to signal motions associated with motionsickness at an early stage, long before these actually cause motionsickness, and allows the driver to adjust his driving style in time. Forthis purpose, the motion sickness indicator 1 can be fitted in thevehicle or to a passenger prior to the drive. Of course, the indicatorcan also be integrated in the vehicle as a standard accessory. Herein,the term ‘vehicle’ is to be construed in a broad sense, including atleast any means of transport on land, but vessels and aircraft alsobelong to the means of transport for which application of the motionsickness indicator 1 is possible. The thus installed motion sicknessindicator 1 will evaluate the motions present in the car during thedrive for their sickening effect and will give feedback on the outcometo the driver or a steering system of the vehicle. In a particularlyadvantageous embodiment, the information presented is differentiated onthe basis of the origin of the motions (braking, accelerating, bends),so the driver can see exactly which driving actions cause motionsickness and how he can adjust these.

The invention is by no means limited to the exemplary embodiment shownin the description and the drawing. Many variations on this example arepossible within the framework of the invention outlined by the claims.

For example, other relevant motion parameters, such as the angularspeed, can be used to predict motion sickness.

These and comparable variations are considered to fall within the scopeof the invention outlined by the claims.

1. A method for the prevention of motion sickness in occupants of avehicle, wherein a motion sickness indicator is fitted in the vehicle,which indicator indicates whether vehicle motions experienced by theoccupants during use can cause motion sickness when the occupants arepersistently exposed to these motions, wherein information coming fromthe indicator is fed back to a driver or a steering system of thevehicle, all this in such a manner that the driver or steering systemcan adjust the steering of the vehicle in such a manner that sickeningmotions are minimized.
 2. A method according to claim 1, wherein themotion sickness indicator measures the vehicle motion, at any rate atleast one parameter thereof relevant for motion sickness, and predictsthe sickening effect of this measured signal on the basis of a relationbetween the measured parameter and motion sickness known from practice,after which the outcome of the evaluation is presented to a driverand/or steering system of the vehicle with the aid of rendering meanssuitable therefor.
 3. A method according to claim 2, wherein theprediction of the indicator is based on the acceleration of the vehiclemotion, which acceleration is measured in at least one direction.
 4. Amethod according to claim 3, wherein the acceleration of the vehiclemotion is measured in three, substantially orthogonal directions (a_(x),a_(y), a_(z)), after which the sickening effect of each accelerationsignal is determined separately, with the aid of a relation specificallydetermined for the direction involved.
 5. A method according to claim 3,wherein the acceleration of the vehicle motion is measured in three,substantially orthogonal directions (a_(x), a_(y), a_(z)), after whichone scalar total acceleration (a) is determined according to a={squareroot}{square root over (a_(x) ²+a_(y) ²+a_(z) ²)}, after which thesickening effect of the vehicle motion is determined on the basis ofthis total acceleration, with the aid of a relation determined on thebasis of practical data.
 6. A method according to any one of the claims3-5, wherein the relation between the measured acceleration and thedegree to which this acceleration can result in motion sickness ismodeled as a transfer function with a band pass characteristic.
 7. Amethod according to any one of the claims 2-6, wherein the relationincorporated in the motion sickness indicator that represents thesusceptibility of the normal population to motion sickness, can beadjusted, during use through interaction of an occupant of the vehiclewith the indicator, to a specific relation that is representative forthe occupant involved.
 8. An apparatus for detecting and signalingpotentially sickening motions, comprising a transducer for measuring arelevant parameter for motion sickness of a motion experienced by theapparatus, evaluation means for comparing the measured motion parameterwith empirical data concerning the sickening effect of comparable motionparameters, on the basis of which the sickening effect of the measuredparameter can be estimated, and rendering means for presenting anoutcome obtained by means of the evaluation means to the user in asuitable manner.
 9. An apparatus according to claim 8, wherein themeasured motion parameter is an acceleration of the motion.
 10. Anapparatus according to claim 8 or 9, wherein the evaluation meanscomprise a band pass filter.
 11. An apparatus according to claim 10,wherein the filter has a peak of between approximately 0.08 and 0.3 Hz,in particular between approximately 0.1 and 0.2 Hz and preferably aroundapproximately 0.16 Hz.
 12. An apparatus according to claim 10 or 11,wherein the band pass filter has a first cut-off frequency of betweenapproximately 0.01 and 0.16 Hz and a second cut-off frequency of betweenapproximately 0.16 and 1 Hz.
 13. An apparatus according to any one ofclaims 9-12, wherein the apparatus comprises adjustment means, foradjusting at least one amplification factor, making the susceptibilityof the apparatus adjustable to an individual user's susceptibility tomotion sickness.
 14. An apparatus according to claim 13, wherein theadjustment means are self-learning.
 15. An apparatus according to anyone of the claims 8-14, wherein the apparatus comprises a housing, whichis provided with fasteners, for fitting the apparatus positionally fixedin, for example, a vehicle or vessel or to a passenger.
 16. An apparatusaccording to any one of the claims 8-15, wherein the evaluation meanscomprise a low-pass filter, for determining a time-dependent degree ofsickening, in particular depending on the motion history, the time overwhich sickening motions occur and/or an average response time of apassenger to such sickening motions.
 17. An apparatus according to claim16, wherein the low-pass filter has a time constant of betweenapproximately 10 and 15 minutes, preferably approximately 12 minutes.18. An apparatus according to any one of the claims 8-17, wherein theevaluation means comprise an integrator, for determining a cumulativedegree of sickening, measured over a specific period of time.